feeding) fish species (cod, haddock, flatfish) and small pelagic fish (herring and
others), pink shrimp and crab. In one statistical subdivision, “area 6”, as throughout
the region from the Grand Banks to New England, a radical collapse of demersal fish
(Fig. 9.10), particularly cod, but also haddock, hake, flatfish, and others, started in the
mid-1980s, led to fishery closures in the early 1990s, without strong recovery through
the years to 2010. There was a parallel increase in many of their prey, particularly
well documented in area 6 for epibenthic shrimp (Pandalus borealis) and snow crab
(Chionocetes opilio), other benthic invertebrates, and small pelagic fish. A food-chain
effect is a reasonable explanation. There may have been a modest decrease of larger
zooplankton, like Calanus and krill, and a substantial increase in phytoplankton was
documented by continuous plankton recorder (CPR) surveys between the 1960s and
1990s (Frank et al. 2005).
Fig. 9.10 (Top) Time-series of demersal fish (“groundfish”) biomass estimates and
fisheries landings on the eastern continental shelf of Nova Scotia in statistical area 6
(Fig. 9.11a). (Bottom) Time-series of abundance estimates in the same region for
small pelagic fish (clupeids primarily), shrimp (Pandalus borealis), and snow crab.
(^) (After Frank et al. 2005.)
Comparisons (Frank et al. 2006) of fisheries agency experimental trawling from